The expected value of each human being is positive

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Soccer player David Beckham and his wife Victoria (formerly a performer) are being derided in the British press as "bad role models." No, they're not publicly carrying on affairs, fighting in public, or abandoning their children. Their sin: having four children.

Boston Globe columnist Jeff Jacoby sees this latest finger-wagging -- including, ominously, scorn from a Member of Parliament -- as just the latest in a string of baseless warnings about overpopulation. Here's Jacoby's rebuttal:

Yes, more babies mean more mouths and therefore more consumption. But more babies also mean more minds and arms and spines - and therefore more new ideas, more effort, more creativity, more initiative, more enterprise. “Human beings do not just consume, they also produce,’’ writes George Mason University economist Bryan Caplan. “The world economy is not like a party where everyone splits a birthday cake; it is more like a potluck where everyone brings a dish.’’

The evidence is obvious. Are we better off today than we were 100 years ago, and 100 years before that? And than we were 2,000 years ago? Obviously.

The advances in health and knowledge have not come from outside agents -- crocodiles and aliens haven't invented penicillin or the lightbulb -- but from the very human beings that population scolds from Malthus to Ehrlich to Friedman tell us are killing the planet.

Sure, many humans consume more than they produce, but on net, over time, humans have clearly added more to human prosperity than they have taken away. Put the way an economist might: the expected value of each human being is positive.